Zhang Shuai shows her sympathy to an injured Madison Keys after their match at the Australian Open.
Photograph: Mark Kolbe/Getty Images

Nine days ago, Zhang Shuai was nearly on a plane back to China before the Australian Open began. The French veteran Virginie Razzano was serving for the match against her in the final round of qualifying, but Zhang was able to break back and win the third set 8-6 — along with a spot in the main draw.

Now, the No133-ranked Zhang, who considered retiring from tennis after a dismal 2015 season, is into the quarter-finals of the season’s first major after defeating an injured Madison Keys 3-6, 6-3, 6-3 on Monday.

Johanna Konta beats Ekaterina Makarova to reach Australian Open last eight

Read more

Keys, who broke through to reach her first grand slam semi-final in Melbourne last year, dominated the first set with powerful groundstrokes that Zhang had trouble returning, breaking the Chinese player at love in the opening game of the match.

But the American began to feel pain in her left leg early in the second set and, after taking a medical timeout to have her upper thigh wrapped, had difficulty putting any weight on her leg to serve and looked increasingly in pain as the match wore on.

She later said she kept playing because “One, I hate retiring. Two, you don’t want to do that to someone who is trying to get into the quarter-finals.”

At the start of the third set, she broke Zhang to take a 2-1 lead. But the trainer returned soon after to treat Keys again and she finished the match slicing shots into the court with no power behind them, tears streaming down her face.

“So difficult to concentrate when I saw her [in pain], it’s so tough to continue to play,” Zhang said in her post-match interview.